U.S. Pat. Nos. 4,693,348, 6,325,191, and 6,615,962, hereby incorporated by reference herein, describe hydraulic torque converters with lockup clutches.
FIG. 1 shows an example prior art hydraulic torque converter 10 including a housing 12 non-rotatably connected to a crankshaft 14 to receive torque from an engine. Housing 12 has coaxial shells 16 and 18 secured and sealed together, for example welded. Attached to housing 12 is a pump 20 coaxial with and sharing the angular velocity of housing 12.
Enclosed in housing 12 are a turbine 22 rotatable with respect to housing 12 and a stator 24 installed between pump 20 and turbine 22. Turbine 22 is non-rotatably connected to a turbine hub 26, and turbine hub 26 is non-rotatably connected to input shaft 28 of a transmission, by splines 30. Stator 24 is mounted on a one-way clutch 32 connected by splines 34 to a hollow, non-rotating stator shaft 36.
Prior art torque converter 10 may further include a lockup clutch 38 capable of being engaged to transmit torque directly between housing 12 and turbine hub 26. This is accomplished by positioning a friction surface 40 of a piston 42 in contact with a friction surface 44 of housing 12. Piston 42 is moveable in both the circumferential and axial directions around turbine hub 26. Axial movement of piston 42 relative to turbine hub 26 may be accomplished by introducing a pressure difference between hydraulic fluid regions 45 and 46 on either axial side of piston 42.
Lockup clutch 38 may also have a torsional vibration damper 48 including a drive plate 50, cover plates 52, 54, a group of coil springs or other elastic energy storing devices 56, and rivets or spacer bolts 58. Drive plate 50 may be connected to piston 42 with splines or crenellations 60. Cover plates 52, 54 retain springs 56 and are held together with rivets or spacer bolts 58. Cover plates 52, 54 may be rigidly connected to turbine 22 and turbine hub 26. Relative circumferential motion between cover plates 52, 54 and drive plate 50 compresses or decompresses springs 56. Torsional damper 48 thereby isolates turbine hub 26 from torsional vibrations coming from, for example, crankshaft 14 or engine.